Physiological and biochemical responses involved in vegetative desiccation tolerance of resurrection plant Selaginella brachystachya

Abstract

The vegetative desiccation tolerance of Selaginella brachystachya has been evaluated for its ability to revive from a desiccation (air dry) state and start normal functioning when rehydrated. In this study, S. brachystachya was identified by DNA barcoding. Experiments were conducted using the detached hydrated, desiccated and rehydrated fronds under laboratory conditions to understand the mechanism of revival upon the water availability. Scanning Electron Microscope images during desiccation showed closed stomata and inside curled leaves. Chlorophyll concentration decreased by 1.1 fold in desiccated state and recovered completely upon rehydration. However, the total carotenoid content decreased 4.5 fold while the anthocyanin concentration increased 5.98 fold and the CO₂ exchange rate became negative during desiccation. Lipid peroxidation and superoxide radical production were enhanced during desiccation by 68.32 and 73.4%, respectively. Relative electrolyte leakage was found to be minimal during desiccation. Activities of antioxidant enzymes, namely peroxidase (158.33%), glutathione reductase (107.70%), catalase (92.95%) and superoxide dismutase (184.70%) were found to be higher in the desiccated state. The proline concentration increased by 1.4 fold, starch concentration decreased 3.9 fold and sucrose content increased 2.8 fold during desiccation. Upon rehydration, S. brachystachya recovered its original morphology, physiological and biochemical functions. Our results demonstrate that S. brachystachya minimizes desiccation stress through a range of morphological, physiological and biochemical mechanisms. These results provide useful insights into desiccation tolerance mechanisms for potential utilization in enhancing stress tolerance in crop plants.

Supplementary information: The online version contains supplementary material available at 10.1007/s13205-021-02667-1.

Keywords: Antioxidants; Desiccation tolerance; Photosynthetic parameters; Proline; REL; ROS; RWC; Resurrection plants; S. brachystachya; Starch; Sucrose; Ultrastructure.

Fig. 1

Morphological changes in detached fronds of S. brachystachya, in hydrated (a), Desiccated (b) and Rehydrated (c). S. brachystachya growing in natural habitat (d). The above bar graph represents the relative waater (RWC) in hydrated (H), desiccated (D) and rehydrated (R) fronds of S. brachystachya. Data represent the means ± SE of three separate experiments at a significant levels *P ≤ 0.01, **P ≤ 0.001, ***P ≤ 0.0001

Fig. 2

Scanning electron micrographs of epidermal surface of hydrated leaves (a, b) desiccated (e, f) and rehydrated (i, j) S. brachystachya. Cross-sectional view of stems in hydrated (c, d) desiccated (g , h) and rehydrated (k, l) S. brachystachya. CW cell wall, CWF cell wall folding, lE leaf, ST stomata, AS air space, PH phloem, XY xylem, CO cortex, EP epidermal. Scale bars are Image a, e and i: 1 mm; d, h and l: 500 µm; c, f, g, j and k: 100 µm

Fig. 3

Pigment composition of S. brachystachya estimated in hydrated (H), desiccated (D) and rehydrated (R) fronds. Total chlorophyll (a), CO₂ exchange rate (b), Anthocyanin (c) and Carotenoids (d). Data represent the means ± SE of three separate experiments, Star indicates significant difference at *P ≤ 0.01, **P ≤ 0.001, ***P ≤ 0.0001

Fig. 4

Activities of antioxidant enzymes quantified in hydrated (H), desiccated (D) and rehydrated (R) fronds of S. brachystachy., a Peroxidase (POD), b Glutathione reductase (GR), c Superoxide dismutase (SOD) and d Catalase (CAT). Data represent the means ± SE of three separate experiments, Star indicates significant difference at *P ≤ 0.01, **P ≤ 0.001, ***P ≤ 0.0001

Fig. 5

a Relative electrolyte leakage (REL) and b Changes in the levels of MDA in hydrated (H), desiccated (D) and rehydrated (R) fronds of S. brachystachya. Data represent the means ± SE of three separate experiments, Star indicates significant difference at *P ≤ 0.01, **P ≤ 0.001, ***P ≤ 0.0001

Fig. 6

Changes in the contents of a Proline, b Sucrose and c Starch in hydrated (H), desiccated (D) and rehydrated (R) fronds of S. brachystachya. Data represent the means ± SE of three separate experiments, Star indicates significant difference at *P ≤ 0.01, **P ≤ 0.001, ***P ≤ 0.0001

Fig. 7

Schematic representation of Morpho-Physiological and Biochemical responses involved during desiccation and rehydration in S. brachystachya